¿Qué es una reacción exotérmica?

Which of the following signs of a chemical reaction are observed in the reaction of potassium with water? precipitate formed temperature change smell produced gas produced color change

When a nucleus absorbs a neutron and then breaks apart, there are many products of the reaction. what is not a product of a nuclear fission reaction

What is the ph of a 0.0010 m hno3? 1.0 3.0 4.0 5.0